Making chemistry accessible for learners with vision impairment

Pupils with vision impairment face significant challenges in learning science. Here, the authors discuss the impact of an inaccessible curriculum and new ideas that can improve accessibility.

make a big difference to accessibility.In graphs and figures, consider using text, symbols and patterns alongside colour, whilst also making gridlines and scales simple and bold 6 .
In school laboratories, accessibility can be improved in surprisingly simple ways.Tactile stickers of different sizes and shapes can be used for labelling.Braille label makers are also available, although these may have limited reach, as many pupils access learning using large print or screen readers.Plastic syringes can be modified with a notch in the barrel to measure specific volumes of liquid 7 .This is something that can be done quickly and cheaply by a school technician, showing that modifications are often thoughtful tweaks rather than expensive purchases.Audio technology is also available, for example talking thermometers, weighing scales or colour detectors.However, it's also important to consider that adaptive technology can give rise to feelings of 'otherness' for a pupil with VI in a mainstream school and so may not be appropriate; it can also cause issues in a noisy classroom, where things may not be heard clearly.

Tactile models
Tactile models can be very effective in illustrating scientific concepts.One example is Tactile Collider, which was designed to make particle accelerator physics accessible to people with VI 8 .Pupils who took part in the project said that it inspired them to learn new things.More importantly, pupils who participated said the experience made them more confident to ask for modifications in school if they felt something was inaccessible.They also said it showed them that further study in the sciences was something they could aspire to.
Another simple example of a tactile demonstration is a building block model of a lithium battery 9 .The wooden pieces of the tower are decorated to represent the oxide and graphite electrodes and the lithium ions.The lithium ion pieces can then be transferred from one tower to gaps in a second tower to represent the charging and discharging processes.Plastic construction bricks have also been used to illustrate concepts such as periodic trends and even molecular orbital theory (Fig. 1) 10 .An important point to note about tactile models is that they should be carefully designed and tested with a VI audience in mind.It's easy to make a tactile version of any scientific diagram but while something may seem obvious to a sighted designer it may not translate well into a tactile form.Complex structures and extensive details can become blurred, and the details lost when models or diagrams are too intricate.This can result in a model which is confusing for a pupil with VI.It is also important to note that models which are simple will still require some level of description in order to allow students to visualise the concepts being delivered.

Experiments using other senses
Much of chemistry education involves experiments and it can be very challenging to make these accessible for pupils with VI.However, some ingenious solutions have been found that rely on senses other than sight to monitor chemical processes and reactions.A fascinating example is the use of onions to detect the endpoint of a titration 11 .Sodium hydroxide inhibits the formation and release of pungent sulfur compounds from onions and neutralisation of the solution with hydrochloric acid releases a strong onion odour.This experiment can be easily adapted for pupils with VI 12 and provides an interesting (albeit smelly) alternative to coloured indicators for sighted pupils.A simple phone app has also been developed to detect the endpoint of titrations using a wide range of coloured indicators 13 .The software is freely available, which maximises accessibility, and the endpoint of a given reaction is signalled by sound or vibration.Olfactory changes have also been used to illustrate the concept of adsorption of organic molecules onto activated carbon 14 and to probe the kinetics of ester formation 15 .

Challenges and outlook
There have been some exciting advances in making chemistry accessible for pupils with VI and this is by no means a comprehensive review.However, there are numerous experiments and areas of chemistry where accessibility has not been considered.Given the attainment gap in secondary school and the fact that so many pupils with VI feel discouraged when accessing science, it is important that the chemistry community works to make school chemistry accessible.A diverse workforce is one which values different skills, and by opening up the chance to study science to

Fig. 1
Fig. 1 Model of the molecular orbital diagram of a B 2 species made with interlocking toy bricks.Small round bricks are used to represent the electrons in (a) the atomic orbitals and (b) the molecular orbitals.A model like this would be used alongside a verbal description.Image reproduced from ref. 10 .